Decoration of g-C3N4 nanosheets by mesoporous CoFe2O4 nanoparticles for promoting visible-light photocatalytic Hg(II) reduction

In this contribution, synthesis of mesoporous CoFe2O4/g-C3N4 heterostructures employing soft and hard templates approaches was explored to produce large surface area (151 m(2) g(-1)) and tight bandgap (2.05 eV) photocatalysts for Hg(II) photoreduction under visible light illumination. TEM image exhibited that CoFe2O4 NPs are well distributed over g-C3N4 nanosheet with a spherical like structure similar to 5-10 nm. The magnetization values for CoFe2O4 NPs and 4%CoFe2O4/g-C3N4 heterostructure were calculated similar to 6.21 and 11.07 emu g(-1), which are very high values compared to the published papers. Mesoporous CoFe2O4/g-C3N4 exhibited a greater photocatalytic efficiency than pure either CoFe2O4 NPs or g-C3N4. Hg(II) photoreduction efficiency boosted from 16.2 % to 100 % as the CoFe2O4 NPs contents increased from 0 to 4% in the mesoporous CoFe2O4/g-C3N4 heterostructures within 60 min. The Hg(II) photoreduction rate goes more quickly over mesoporous 4%CoFe2O4/g-C3N4 (539.91 mu molg(-1) h(-1)) as compared to pure either g-C3N4 (79.86 mu molg(-1) h(-1)) and CoFe2O4 NPs (117.25 mu molg(-1) h(-1)). The key factor for promoting Hg(II) photoreduction is the highly dispersed CoFe2O4 NPs onto the surface of g-C3N4 and their large surface area, narrow bandgap, small particles size, harvest light and high diffusion of Hg(II) into the pores. Mesoporous CoFe2O4/g-C3N4 are magnetically removable easily possessing a high recyclability and durability in the Hg(II) photoreduction in aqueous solutions.